The assembly of the membrane-bound formate-nitrate electron transport pathway in Escherichia coli will be studied to elucidate the general principles and molecular mechanisms involved in the biogenesis of organized cellular elements. This pathway involves three enzyme components, formate dehydrogenase, cytochrome b1 and nitrate reductase; these components are composed of a total of six polypeptides and contain several metals and cofactors. The formation of the pathway is under the control of seven genes. Studies are proposed which are aimed at defining the structural features of the components which are responsible for their integration into the membrane and their interaction to form a functional multi-enzyme complex. Genetic studies are proposed to elucidate the specific roles of the genes in the biogenesis of the pathway. Procedures to be developed in these studies will be used to analyze the sequence of events involved in the assembly of this multi-component pathway in the membrane.